Current control circuit for electro-erosion machine

A control circuit for a wire cutting electric discharge machine comprising: a power circuit for applying a pulse voltage at a working gap between a wire electrode and a workpiece; a idscriminant circuit for detecting a discharge status of the working gap, said discriminant circuit detecting the voltage at the working gap and generating a first output signal in the event said voltage remains below a standard voltage within a predetermined time period after a time when a pulse voltage is applied to the working gap; a counter for calculating the number of first output signals generated by the discriminant circuit; a discharge-ON time interval setting circuit for setting a discharge-ON time interval during which a discharge current is actually passed through the working gap; a discharge-OFF time interval setting circuit for setting a discharge-OFF time interval; a pulse control circuit for controlling the discharge-ON and OFF time intervals in accordance with signals from the discharge-ON and OFF time interval setting circuits, said pulse control circuit extending the OFF-time intervals of thelse when the calculated value of the number of successive first output signals, in the counter, reaches a set value; and a drive circuit for driving, by means of the output of the pulse control circuit, a switching element which is connected into the power circuit L'INVENTION CONCERNE UN CIRCUIT DE COMMANDE POUR MACHINES A DECHARGES ELECTRIQUES DE COUPE.IL COMPREND UN CIRCUIT D'ALIMENTATION 3 SERVANT A APPLIQUER UNE IMPULSION DE TENSION SUR UN INTERVALLE DE TRAVAIL 1 FORME ENTRE UNE ELECTRODE EN FIL ET UNE PIECE, UN CIRCUIT DE DISCRIMINATION 13 QUI DETERMINE L'ETAT DES DECHARGES DANS L'INTERVALLE DE TRAVAIL, UN COMPTEUR 15 QUI CALCULE LE NOMBRE DE DECHARGES ANORMALES QUI ONT ETE DETERMINEES PAR LE CIRCUIT DE DISCRIMINATION, UN CIRCUIT 17, 19, 21 DE COMMANDE D'IMPULSION QUI PROLONGE L'INTERVALLE DE TEMPS DE NON-EXISTENCE DE L'IMPULSION LORSQUE LA VALEUR CALCULEE POUR LE NOMBRE DE DECHARGES ANORMALES SUCCESSIVES, QUI A ETE CALCULEE DANS LE COMPTEUR, ATTEINT UNE VALEUR DONNEE ET UN CIRCUIT D'EXCITATION 11 QUI COMMANDE GRACE AU SIGNAL DE SORTIE DU CIRCUIT DE COMMANDE D'IMPULSION UN ELEMENT DE COMMUTATION 9 QUI EST CONNECTE AU CIRCUIT D'ALIMENTATION ELECTRIQUE